This invention relates to a process for the permanent deforming of keratin fibers, more especially human hair, by reductive cleavage and oxidative re-establishment of disulfide bonds of the keratin and to preparations suitable for this process.
The permanent deforming of keratin fibers is normally carried out by mechanically deforming the fibers and fixing the deformation by suitable auxiliaries. Before and/or after their deformation, the fibers are treated with an aqueous preparation of a keratin-reducing substance and, after a contact time, are rinsed with water or with an aqueous solution. In a second step, the fibers are treated with an aqueous preparation of an oxidizing agent. After a certain contact time, the oxidizing agent is also rinsed out and the mechanical deforming aids (curlers, rollers) are removed from the fibers.
The aqueous preparation of the keratin reducing agent is normally alkalized so that, on the one hand, enough of the thiol functions are deprotonated and, on the other hand, the fiber swells so that the keratin-reducing substance is able to penetrate deeply into the fiber. The keratin-reducing substance splits some of the disulfide bonds of the keratin to —SH groups, so that the peptide linkage is loosened and, through the stretching of the fibers by their mechanical deformation, the keratin structure is re-oriented. Under the influence of the oxidizing agent, disulfide bonds are re-established and, in this way, the deformation which the keratin structure has undergone is fixed. A known process of the type in question is the permanent waving of human hair. This process may be applied both to produce curls and waves in straight hair and to straighten curly hair.
Unfortunately, a negative side effect of the permanent waving of hair carried out in this way is that the hair often becomes brittle and dull. In addition, other properties, such as wet and dry combability, feel, flexibility, softness, luster and tear strength, are also adversely affected in many cases.
Accordingly, there has been no shortage of attempts in the past to remedy this situation.
A corresponding modification of the reducing solution leads to generally unsatisfactory waving performance. Although the addition of known additives, such as structurants, polymers, film formers and crosslinking resins, or the adjustment of the preparation to a neutral or mildly acidic pH can reduce the damage done to the hair, the hair remains more or less weakened in its structure. Although care of the hair by further aftertreatments can again improve the properties of the hair, it does take more time and, in general, involves the use of at least one other formulation.
Accordingly, there was still a need to find a process for permanently deforming keratin fibers in which the unwanted side effects mentioned would be further reduced or eliminated altogether.
It has now surprisingly been found that a significant improvement in the properties of deformed keratin fibers, such as improved combability and condition, can be achieved if at least one preparation used during the deforming process is formulated as a multiphase preparation and contains special compounds.